The invention relates to an electromagnetic relay, which exhibits the following features:
an insulating base body, PA1 at least one coil, disposed on the base body, with a winding and a core, PA1 a yoke connected to a first end of the core, PA1 an armature which is mounted on the yoke and which forms an air gap with the second end of the core, PA1 at least one contact spring, which is disposed between armature and coil and which is pivotably secured, in the vicinity of the armature bearing position, to a holding pin anchored in the base body and can be switched over, by its free end, by the armature between a neutral position and a working position, and PA1 at least one countercontact element, which is anchored in the base body and which, in a specified switching position of the armature, closes a load current circuit with the contact spring, PA1 the holding pin being situated within the ferromagnetic circuit formed by the yoke, the armature and the core and the countercontact element being situated, at least by a connecting portion, outside this ferromagnetic circuit.
With the arrangement, provided in this construction, of the contact spring between armature and coil, it is possible to create a compact relay construction; in this case, the contact spring is actuatable in a simple manner directly by the armature when the latter is attracted to the core. This arrangement of the contact spring is particularly advantageous in the construction of a switchover relay, forming the subject of the older, non-prior-published European Patent Application No. 91111423.9. In that case, two separately drivable coils with in each case one winding and in each case one core are aligned substantially axially in relation to one another on the base body; in this case, an air gap is formed between the mutually facing inner core ends and the outer core ends are connected to a yoke. By means of an armature mounted at a center region of the yoke, contact springs disposed in that case in each instance between the armature and the coil can be switched over by the armature optionally between a neutral position and a working position; in this case, at least two stationary countercontact elements anchored in the base body provide contact in each instance at least with one contact spring in at least one of their switching positions.
The arrangement, provided here, of a holding pin for a contact spring in the region between armature and coil can influence the function of the relay insofar as via the contact spring with a bearing pin serving as a connecting pin and the countercontact element when the contact is closed, a current loop conducted through the ferromagnetic circuit of the core, the yoke and the armature can be formed, the magnetic field of which is superposed upon the exciter circuit of the coil. Depending upon the direction of flow in this current loop, the additionally generated magnetic flux can be directed in the same direction as the exciter flux or in the opposite direction thereto and can thus intensify or weaken the attractive force on the armature. A problem can however arise where a very high load current flows via a closing contact when the armature has been attracted and this load current, by means of its magnetic field, holds the armature fast, in the attracted condition, even after deenergization of the excitation, so that the armature cannot fall away any longer. As long as only a simple relay with one contact spring and one connecting pin between the armature and the coil is involved, such a condition can be eliminated by appropriate polarity of the load current connections. However, in the case of a switchover relay with two series-connected coils, an intermediate armature and with contact springs on each side of the armature, such a compensation can be carried out only in one direction, so that the mentioned problem can arise in the case of extremely high contact currents.